2(2 



NEW fiENKRA AND SPECIES OF CYSTIDEA. 



[1854. 



tbis vicinity, by Dr. Bigsby, find by bim taken to England. An- 

 other specimen was found by Mr. Gibba (of the Geological Sur- 

 rej of England), Dear Yspett} Evan, in North Wales, in :t ma 

 of schistose rock, from a quarry associated with the Bala limestone, 

 a formation which has furnished man\ species of Cystidea, and 

 which appears to occupy the same palaeontologies] level as the 



TrentOn limestone. In describing lie- la-t nil Ml iiiuM 



l'rol'c-sor Forbes stales: — 



" One of the most remarkable Cystideans asyel discovered in 



British strata is a fossil which rewarded the exertions of the col- 

 lectors for the Survey in North Wales during the summer of 

 lb-1-7. It is a hemispherical, many plated, spheronite-like body, 

 but presenting the striking characteristic of possessing five ser- 

 pentine grooves, radiating from its mouth, and occupied by as 

 many appressed arms. Within one of the compartments formed 

 by the surrounding arms is an ovarian pyramid. Thus it exhi- 

 bits characters which in some degree link the very different types, 

 Pseudocrinites and Spheronztes. 



"Although no similar European form had been described by 

 any author, its aspect immediately called to mind a remarkable 

 American fossil, figured and described by Mr. G. B. Sowerby, in 

 the second volume of the Zoological Journal." The body in ques- 

 tion was discovered by Dr. Bigsby in Canada, and Mr. Sowerby 

 describes it as follows: — 



" Upon examination of this fossil, we do not immediately re- 

 cognise its affinities, for it bears so near a resemblance to the arms 

 of an Asterias lying on an Echinus; we think, however, judging 

 from the want of ambulacra, that it would be properly placed 

 among the genera of the As/eriadce. At the same time, its vici- 

 nity in general form to Say's family oiBlastoidea renders it doubtful 

 whether it ought not to be considered as a connecting link to be 

 placed between the two families of Crinoidea and Blastoidca, 

 and this suggestion obtains support from the apparently lateral situ- 

 ation of the mouth, in which it resembles some of the Crinoidea. 

 This suggestion, however, involves the following consideration, 

 namely, whether those rays in the Blastoidca, which, by Say, are 

 called ambulacra (a term commonly applied to au apparently cor- 

 responding part in the Echinida), really serve the same purpose, 

 or whether they be not arms, as in the other Crinoidea. And I 

 venture to assert that there is nothing, either in their position or 

 form, that militates against such an idea. 



" I hope the following description, together with the figure by 

 which it will be accompanied, will serve to give as correct an idea 

 of the fossil in question as cau be conveyed without the actual 

 examination of the specimen. 



" The general form, as far as we can judge from the specimen, 

 in which none of the lower part is preserved, is a depressed sphe- 

 roid, and it does not appear to have naturally any angular promi- 

 nences, though, owing to the circumstance of its being divided 

 into five sections, it might possibly be very obtusely pentagonal. 

 It appears to have consisted of a number of irregular partly im- 

 bricated, crustaceous plates, and its upper half is divided into five 

 sections or compartments, by five equal arms, which diverge from 

 the centre, and are curved all iu the same direction. 



"The compartments are not equal in size; in the largest of 

 them, and near its centre, is placed the mouth, which appears to 

 have been surrounded by two or three rows of very minute, im- 

 bricated, crustaceous scales; the arms, five in number, all dimi- 

 nishing to a point at their outer extremity, and having their upper 

 portion elevated above the body, seem, however, to be attached 



to ii by th.-ir un.l.r ride, ami indeed partly bedded in it; each one 

 is divided into two equal part •■ . a longitudinal groove, and each 

 of these parts is again di\ ided into a oumbei of seg ats by trans- 

 fer* and dei p groovi . which are close i about half their 

 length distant from each other. 1 cannot ascertain whether there 

 is any natural opening in the centre or not The whole is chat 

 into crystalline carbonate of lime, coloured by iron rust, and it 

 lies upon a ma imi stone, a ntaining a mass of Encrini and 



Madrcporitcs; a single spiral univalve is also to 1 bserved. 



From the Falls of the t'haudiere on the Ottawa River in Lower 

 Canada." 



In reference to these remarks of Mr. Sowerby, Professor Forbes 

 observes : — 



"Although the true affinities of this curious fossil are not re- 

 cognised in this description, and many of the parts misinterpr. 

 (as, for example, the ovarian pyramid is regarded as the mouth), 

 still there can be no question, especially when the characteristic 

 figure which accompanies the paper is examined, of il- true posi- 

 tion being among the Cystideans, and of its being generically 

 allied to the British fossil we are about to describe." — Mem. Geo. 

 Stir., Vol. I., p. 519. 



In one locality near Bytown in the Trenton limestone I found 

 seven specimens of the fossil above described by Mr. Sowerby 

 lying near each other, within a space of four square yards 

 in extent, and partially imbedded in the surface of a stratum 

 of limestone. Along with them were three new species of emii- 

 nites, the Cystidean last described, several tiibolites, and a great 

 quantity of the coral Chetetes lycoperdon. I succeeded in clear- 

 ing from the matrix one specimen, consisting of three of the rays 

 and four sides of the mouth, so that both sides of the shell can be 

 seen. 



It shows an important character not previously observed, and 

 which appeai-s to affect the zoological rank of the fossil very 

 materially. The rays are not grooves for the reception of arms, 

 as has been supposed, but appear to be ambulacra, resembling those 

 of the Echinida;. 



They are composed each of two rows of oblong pentagonal 

 plates, and are perforated between the joints by two single rows 

 of very large pores, which open out on the interior in the same 

 manner as on the exterior. The mouth is large and five-sided, 

 as shown in the figure. The supposed ovarian aperture consists 

 of a space between two of the rays, covered by a number of plates 

 much smaller than the average size. They form an elevation, the 

 apex of which has been shattered, so that it cannot be determined 

 whether there was in this place an ovarian pyramid or not This 

 part is only preserved in one of my specimens, and it is from this 

 that I have drawn the corresponding part in the figure. Another 

 specimen shows the plates on the other side except in the 

 centre, where there appears to have been a round opening three- 

 eighths of an inch in diameter. It is much distorted, however, 

 and the plates are obscurely seen, so that nothing can be asserted 

 concerning it with certainty. In this one, also, it is remarkable 

 that the rays turn to the right instead of the left, as in all the 

 others. 



The figure given above is a restoration, showing the structure 

 of the fossil, as seen in the specimens in my possession, one of 

 which is nearly as perfect as the figure itselt. 



All the appearances about this fossil negative the idea that 

 these grooved rays were occupied by arms. 



